Fix constructor order in unit tests (sanitizer)

The WithParamTest constructor needs to be called first, as the
EncoderTest constructor is called with 'GET_PARAM'.

BUG=aomedia:580

Change-Id: I17f3c02c0a0eec103fb3505301b5eb6dfdef851c
diff --git a/test/active_map_test.cc b/test/active_map_test.cc
index a926b0f..e38aa17 100644
--- a/test/active_map_test.cc
+++ b/test/active_map_test.cc
@@ -20,8 +20,8 @@
 namespace {
 
 class ActiveMapTest
-    : public ::libaom_test::EncoderTest,
-      public ::libaom_test::CodecTestWith2Params<libaom_test::TestMode, int> {
+    : public ::libaom_test::CodecTestWith2Params<libaom_test::TestMode, int>,
+      public ::libaom_test::EncoderTest {
  protected:
   static const int kWidth = 208;
   static const int kHeight = 144;